Airborne asbestos contamination in buildings is a significant environmental problem. Various diseases have been linked with industrial exposure to airborne asbestos, and the extensive use of asbestos products in buildings has raised concerns about exposure to asbestos in nonindustrial settings. Surveys conducted by the Environmental Protection Agency (EPA) estimate that asbestos-containing materials can be found in approximately 321,000 schools and 733,000 other public and commercial buildings in this country.
In an effort to avoid the hazards associated with exposure to airborne asbestos, abatement actions or procedures are being extensively conducted and the Environmental Protection Agency has published a booklet entitled "Guidance for Controlling Asbestos-Containing Materials in Buildings." During the abatement action, one or more air filtration units, usually several air filtration units, are positioned throughout the work site to filter the air in the work place and to maintain a negative pressure within the space within which the abatement procedure is being conducted. It is important to maintain the negative pressure within the work area so that airborne asbestos fibers will not escape therefrom. In other words, by maintaining a negative pressure within the work space, air will tend to be drawn into the work area rather than being expelled or discharged therefrom.
It is therefore important to be able to monitor the negative air pressure within the work area to ensure that airborne fibers cannot escape therefrom. In applicant's co-pending application entitled "Remote Control and Monitor Means", Ser. No. 191,567 filed Apr. 9, 1988, a means was provided to sense the negative air pressure within the contaminated work space immediately adjacent the clean room area. However, it has been found that even though the desired negative pressure may be present at a particular location within the work space, the desired negative pressure may not exist at other locations within the work space. Further, it has been found desirable to be able to have a record of the negative air pressure within the work space for the period of time that the abatement procedure is being conducted.